1. Field of the Invention
The invention relates to a stepping motor driving device and a timepiece.
2. Description of the Related Art
In the related art, a stepping motor configured to rotate forward and reversely is used for a timepiece and the like. For example, a stepping motor disclosed in JP-A-2014-195371 includes a rotor for which two-pole magnetization has been performed, three magnetic poles arranged around the rotor at an interval of 90 degrees, and coils wound on the two magnetic poles of the three magnetic poles. By appropriately applying driving pulses to the two coils, the stepping motor is rotated.
According to the technology disclosed in JP-A-2014-195371, when rotating the stepping motor, there are a time period for which only one of the two coils is energized and a time period for which both the two coils are energized. In this case, a peak of consumption current (current output from a battery cell) appears in the latter time period. Here, when the latter time period is made to be shorter than the former time period, the energy that is to be consumed in the stepping motor can be made to be substantially the same in both the time periods. However, the power that is to be consumed due to an internal resistance of the battery cell and the like is proportional to a square of the consumption current. Therefore, according to the technology disclosed in JP-A-2014-195371, the power that is to be consumed in the latter time period increases, so that the battery cell is rapidly drained.